1. Field of the Invention
The invention relates to a heating or air-conditioning system for a motor vehicle, by means of which individual air-conditioning zones of the vehicle interior can be supplied with separately temperature-controlled air.
2. Description of the Related Art
FR 2717747 discloses an air-conditioning installation by means of which the air fed to the various air-conditioning zones, namely the “front right” (passenger seat) and “front left” (driver's seat) zones and the “rear left” and “rear right” zones, can be adjusted separately. For this purpose, the air-conditioning installation has two air-conditioning systems, one supplying the left-hand half of the vehicle and the other supplying the right-hand half of the vehicle. Each of the air-conditioning systems can be used to supply the front region and rear region with differently temperature-controlled air. This air-conditioning installation involves very high outlay since it has two air-conditioning systems, each with a fan, evaporator and heater and corresponding air lines. The system is thus correspondingly cost-intensive and, as a result of the large amount of space that it requires, can only be used in large-capacity vehicles.
DE 39 40 361 discloses an air-conditioning system by means of which four air-conditioning zones can be supplied. In this air-conditioning system, warm air and cold air are produced and fed to each air-conditioning zone via separate ducts. In the region of the air-outlet openings arranged in the respective air-conditioning zone, there is provided for each air-conditioning zone a mixing space, in which warm air and cold air can be mixed immediately before they emerge into the vehicle interior. Although such an air-conditioning system can supply four air-conditioning zones with just one fan, one evaporator and one heater, the air ducts require a considerable amount of installation space since, for the air supply for each air-conditioning zone, it is necessary to provide two air ducts, which each open out into a mixing space. A further disadvantage is that the warm air and cold air are only mixed immediately before they emerge from the air-outlet nozzles, with the result that mixing is often insufficient and hot and cold air masses emerge one beside the other from an air-outlet nozzle.
U.S. Pat. No. 5,016,704 discloses a motor-vehicle air-conditioning system by means of which just two air-conditioning zones, namely the front region and the rear region, can be differently air conditioned. This air-conditioning system is divided in two downstream of the evaporator. In each sub-region, an air flux regulates the quantity of air that is heated by the heater or is routed past the heater. Warm air and cold air can mix downstream of the heater and are fed to the individual outlet nozzles. The disadvantage with this air-conditioning system is that it requires a large amount of installation space and good air mixing is not ensured. Furthermore, it is only possible for two zones to be air conditioned.
DE 44 22 120 discloses an air-conditioning system which has left/right regulation. In order to obtain a compact design, the cold air is routed past the heat exchanger laterally and mixed with the warm air behind the heat exchanger. Despite the already more compact design, the amount of installation space required by this air-conditioning system on account of the warm-air pivot flaps, which are located downstream of the heat exchanger and execute a pivot movement into the mixing space, is relatively large. A further disadvantage is that optimum mixing of cold air and warm air is not ensured since, even in its open state, the warm-air pivot flap separates the cold and warm air masses to a certain extent. Furthermore, this air-conditioning system is not suitable for supplying more than two air-conditioning zones.